Hands-On RTOS with Microcontrollers

External memory support

In higher pin count packages, expect to find support for static random access memory (SRAM). Synchronous dynamic random access memory (SDRAM) support, with an on-board controller taking care of the tight timing requirements and refresh cycles, can be found in higher performance devices. Devices aimed at performance will generally bring in support for quad-SPI. Often, external RAM—and even quad-SPI devices—can be memory-mapped and used similar to internal storage, albeit with a performance hit. Many devices have MultiMediaCard (MMC) and secure digital card (SD card) controllers as well, so commodity consumer-grade removable storage is easily added.